document.write( "Question 896278: If A can Fill tank in 20 min and B can empty that tank in 30 min, If they work alternatively 1 min, then how much time has been taken to filled the tank completely. \n" ); document.write( "
Algebra.Com's Answer #543370 by josgarithmetic(39800)\"\" \"About 
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A and B alternate over a 2 minute period for some quantity of these periods.\r
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\n" ); document.write( "\n" ); document.write( "\"%281%2F20%29%2A1-%281%2F30%29%2A1\", a two minute period.
\n" ); document.write( "Same as (1/20-1/30)*p, using p to count the number of these two-minute periods.\r
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\n" ); document.write( "\n" ); document.write( "Fill 1 tank.
\n" ); document.write( "\"%281%2F20-1%2F30%29p=1\"
\n" ); document.write( "\"%283%2F60-2%2F60%29p=1\"
\n" ); document.write( "\"%281%2F60%29p=1\"
\n" ); document.write( "\"p=60\", the count of the two-minute alternating time periods.\r
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\n" ); document.write( "\n" ); document.write( "This means, \"2%2Ap=2%2A60=120\" minutes,
\n" ); document.write( "2 hours.
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